<template>
    <div class="shop-cart">
      <div class="content" @click="toggleList">
        <div class="content-left">
          <div class="logo-wrapper">
            <div class="logo" :class="{'highLight':totalCount>0}">
              <i class="icon-shopping_cart" :class="{'highLight':totalCount>0}"></i>
            </div>
            <div class="num" v-show="totalCount>0">{{totalCount}}</div>
          </div>
          <div class="price" :class="{'highLight':totalPrice>0}">{{totalPrice}}元</div>
          <div class="desc">另需配送费&yen;{{deliveryPrice}}元</div>
        </div>
        <div class="content-right" @click.stop.prevent="pay">
          <div class="pay" :class="payClass">{{payDesc}}</div>
        </div>
      </div>
      <div class="ball-container">
        <transition name="drop" v-for="(item, index) in balls" :key="index" @before-enter="beforeDropped" @enter="dropped" @after-enter="afterDropped">
          <div class="ball" v-show="item.show">
            <div class="inner inner-hook"></div>
          </div>
        </transition>
      </div>
      <transition name="fold">
        <div class="shop-cart-list" v-show="showList">
          <div class="list-header">
            <h1 class="title">购物车</h1>
            <span class="empty" @click="clearCart">清空</span>
          </div>
          <div class="list-content" ref="listContent">
            <ul>
              <li class="food" v-for="(food, index) in selectFoods" :key="index">
                <span class="name">{{food.name}}</span>
                <div class="price">
                  <span>￥{{food.price * food.count}}</span>
                </div>
                <div class="cart-ctrl-wrapper">
                  <v-cart-ctrl :food="food"></v-cart-ctrl>
                </div>
              </li>
            </ul>
          </div>
        </div>
      </transition>
      <transition name="fade">
        <div class="list-mask" @click="hideList" v-show="showList"></div>
      </transition>
    </div>
</template>

<script>
import BScroll from 'better-scroll'
import CartCtrl from '@/components/cartcontrol/CartCtrl'

export default {
  props: {
    selectFoods: {
      type: Array,
      default () {
        return []
      }
    },
    deliveryPrice: {
      type: Number,
      default: 0
    },
    minPrice: {
      type: Number,
      default: 0
    }
  },
  components: {
    'v-cart-ctrl': CartCtrl
  },
  data () {
    return {
      // 创建5个小球用于动画
      balls: [
        {
          show: false
        },
        {
          show: false
        },
        {
          show: false
        },
        {
          show: false
        },
        {
          show: false
        }
      ],
      // 存储下落小球
      dropBalls: [],
      // 折叠状态
      fold: true
    }
  },
  computed: {
    totalPrice () {
      let total = 0
      this.selectFoods.forEach((food) => {
        total += food.price * food.count
      })
      return total
    },
    totalCount () {
      let count = 0
      this.selectFoods.forEach((food) => {
        count += food.count
      })
      return count
    },
    payDesc () {
      if (this.totalPrice === 0) {
        return `￥${this.minPrice}元起送`
      } else if (this.totalPrice < this.minPrice) {
        let diff = this.minPrice - this.totalPrice
        return `还差￥${diff}元起送`
      } else {
        return '去结算'
      }
    },
    payClass () {
      return this.totalPrice < this.minPrice ? 'not-enough' : 'enough'
    },
    showList () {
      if (!this.totalCount) {
        // this.fold = true
        return false
      }
      let show = !this.fold
      return show
    }
  },
  methods: {
    drop (el) {
      for (let i = 0; i < this.balls.length; i++) {
        let ball = this.balls[i]
        if (!ball.show) {
          // 只有改变元素显示隐藏状态才会触发 过渡钩子函数
          ball.show = true
          ball.el = el
          this.dropBalls.push(ball)
          return
        }
      }
    },
    beforeDropped (el) {
      let count = this.balls.length
      while (count--) {
        let ball = this.balls[count]
        if (ball.show) {
          // 浏览器接口 getBoundingClientRect()可以获取到元素对象和窗口的相对上下左右的距离
          let rect = ball.el.getBoundingClientRect()
          // 小球x轴方向位移= 小球距离屏幕左侧的距离-外层盒子距离水平的距离
          let x = rect.left - 32
          // y轴：负数，因为是从左上角向下
          let y = -(window.innerHeight - rect.top - 22)
          el.style.display = ''
          // 纵向动画
          el.style.webkitTransform = `translate3d(0, ${y}px,  0)`
          el.style.transform = `translate3d(0, ${y}px, 0)`
          // 横向动画  inner-hook，  仅仅定义类 dom选择器，不做样式
          let inner = el.getElementsByClassName('inner-hook')[0]
          inner.style.webkitTransform = `translate3d(${x}px, 0, 0)`
          inner.style.transform = `translate3d(${x}px, 0, 0)`
        }
      }
    },
    dropped (el, done) {
      /* eslint-disable no-unused-vars */
      // 手动触发浏览器重绘，便于translate3d，--refresh 变量不会使用
      let refresh = el.offsetHeight
      this.$nextTick(() => {
        // 小球样式位置，置于购物车按钮位置处
        el.style.webkitTransform = 'translate3d(0, 0, 0)'
        el.style.transform = 'translate3d(0, 0, 0)'

        let inner = el.getElementsByClassName('inner-hook')[0]
        inner.style.webkitTransform = 'translate3d(0, 0, 0)'
        inner.style.transform = 'translate3d(0, 0, 0)'

        el.addEventListener('transitionend', done)
      })
    },
    afterDropped (el) {
      // 此轮动画结束后，将此次的 ball 取出 ，ball状态重置，，el display:none
      let ball = this.dropBalls.shift()
      if (ball) {
        ball.show = false
        el.style.display = 'none'
      }
    },
    toggleList () {
      if (!this.totalCount) {
        return
      }
      this.fold = !this.fold
    },
    clearCart () {
      this.selectFoods.forEach((food) => {
        food.count = 0
      })
    },
    hideList () {
      this.fold = true
    },
    pay () {
      if (this.totalPrice < this.minPrice) {
        return
      }
      window.alert(`支付${this.totalPrice}元`)
    }
  },
  watch: {
    selectFoods (newFoods, oldFoods) {
      if (newFoods.length === 0) {
        this.fold = true
      }
    },
    showList () {
      let show = !this.fold
      if (show) {
        this.$nextTick(() => {
          if (!this.scroll) {
            this.scroll = new BScroll(this.$refs.listContent, {
              click: true
            })
          } else {
            this.scroll.refresh()
          }
        })
      }
    }
  }
}
</script>

<style lang="stylus" scoped>
  @import "../../common/stylus/mixin.styl"
  .shop-cart
    position: fixed
    left: 0
    bottom: 0
    z-index: 50
    width: 100%
    height: 48px
    background: #000
    .content
      display: flex
      background: #141d27
      font-size: 0
      color: rgba(255, 255, 255, 0.4)
      .content-left
        flex: 1
        .logo-wrapper
          display: inline-block
          vertical-align: top
          position: relative
          top: -10px
          margin: 0 12px
          padding: 6px
          width: 56px
          height: 56px
          box-sizing: border-box
          border-radius: 50%
          background: #141d27
          .logo
            width: 100%
            height: 100%
            border-radius: 50%
            background: #2b343c
            text-align: center
            &.highLight
              background: rgb(0, 160, 220)
            .icon-shopping_cart
              font-size: 24px
              line-height: 44px
              color: #80858a
              &.highLight
                color: #fff
          .num
            position: absolute
            top: 0
            right: 0
            width: 24px
            height: 16px
            line-height: 16px
            text-align: center
            border-radius: 16px
            font-size: 9px
            font-weight: 700
            color: #fff
            background: rgb(240, 20, 20)
            box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.4)
        .price
          display: inline-block
          vertical-align: top
          margin-top: 12px
          line-height: 24px
          padding-right: 12px
          box-sizing: border-box
          border-right: 1px solid rgba(255, 255, 255, 0.1)
          font-size: 16px
          font-weight: 700
          &.highLight
            color: #fff
        .desc
          display: inline-block
          vertical-align: top
          margin: 12px 0 0 12px
          line-height: 24px
          font-size: 10px
      .content-right
        flex: 0 0 105px
        width: 105px
        .pay
          height: 48px
          line-height: 48px
          text-align: center
          font-size: 12px
          font-weight: 700
          background: #2b333b
          &.not-enough
            background: #2b333b
          &.enough
            background: #00b43c
            color: #fff
    .ball-container
      .ball
        position: fixed
        left: 32px
        bottom: 22px
        z-index: 200
        transform: translate3d(0, 0, 0)
        transition: all 0.6s cubic-bezier(0.49, -0.29, 0.75, 0.41)
        .inner
          width: 16px
          height: 16px
          border-radius: 50%
          background: rgb(0, 160, 220)
          transition all 0.6s linear
          transform translate3d(0, 0, 0)
    .shop-cart-list
      position: absolute
      left: 0
      top: 0
      z-index: -1
      width: 100%
      transform: translate3d(0, -100%, 0)
      .list-header
        height: 40px
        line-height: 40px
        padding: 0 18px
        background: #f3f5f7
        border-bottom: 1px solid rgba(7, 17, 27, 0.1)
        .title
          float: left
          font-size: 14px
          color: rgb(7, 17, 27)
        .empty
          float: right
          font-size: 12px
          color: rgb(0, 160, 220)
      .list-content
        padding: 0 18px
        max-height: 217px
        overflow: hidden
        background: #fff
        text-align: left
        .food
          position: relative
          padding: 12px 0
          box-sizing: border-box
          border-1px(rgba(7,17, 27, 0.1))
          .name
            line-height: 24px
            font-size: 14px
            color: rgb(7,17, 27)
          .price
            position: absolute
            right: 90px
            bottom: 12px
            line-height: 24px
            font-size: 14px
            font-weight: 700
            color: rgb(240, 20, 20)
          .cart-ctrl-wrapper
            position: absolute
            right: 0
            bottom: 6px
    .fold-enter, .fold-leave-to
      transform: translate3d(0, 0, 0)
    .fold-enter-active, .fold-leave-active
      transition all 0.5s
  .list-mask
    position: fixed
    top: 0
    left: 0
    width: 100%
    height: 100%
    z-index: -40
    opacity: 1
    background: rgba(7, 17, 27, 0.6)
    backdrop-filter: blur(10px)
  .fade-enter,.fade-leave-to
    opacity: 0
  .fade-enter-active, .fade-leave-active
    transition: all 0.1s linear
</style>
